SOURCES OF SOIL POLLUTION IN SOUTH AMERICA

The relevance of this work lies in the fact that today the soils of South America are highly polluted and the destruction of the soil cover can lead to a reduction in natural resources. The main soil pollutants are divided into chemical, physical and biological. The main sources of soil pollution are: industry; transport; Agriculture; utilities; landfills; mining industry; Atomic industry. The main sources of soil pollution in South America are: agriculture, municipal solid waste, mining and smelting activities, and transport infrastructure and emissions.

The amount of land in the region used for irrigated crop production has increased since 2000, and the livestock and aquaculture industries are also growing. Indeed, during the last decades of the 20th century, these industries increased by approximately 20%, resulting in severe impacts on ecosystems. The expansion of these activities influences land use changes and influences deforestation, soil degradation, biodiversity loss and greenhouse gas emissions [3, 230 p]. Latin America has the highest average pesticide use per arable area in the world. While the amount of pesticides doubled in Central America and increased by 33 percent in the Caribbean, the most significant increase occurred in South America, where pesticides increased by 500 percent between 1990 and 2017 (Pic 1). According to World Bank data on fertilizer consumption in the region, there was a 50 percent increase from 2002 to 2016 (Graph  2) from 89.5 kg/ha to 140.2 kg/ha. According to 2015 FAO data, annual fertilizer use in the region is expected to increase by 3.3 percent [7].

Pic/ 1. Average pesticide use per cropland area (kg/ha) between 1990 and 2017 [9]

Graph 1. Fertilizer consumption in the Latin American region from 2002 to 2016 [9]

Livestock raising is also an important activity, mainly in South America, and manure is often applied to the soil as an organic fertilizer. Excess nitrogen in the soil can also lead to deterioration of the root system, soft tissue, plant weakness, production delays, poor crop quality, and increased susceptibility to diseases and pests [4, 110 p]. In South America, the situation varies greatly from country to country. Erosion can facilitate the migration of dust from eroded bare soil, which can lead to the dispersion of contaminated soil particles. Such dispersion affects surface and groundwater bodies and remote agricultural areas [3, 28 p]. Turning to the topic of biological factors, it is important to note that this type of pollution sometimes occurs as a result of the accidental natural introduction of organisms alien to a given territory [5].

Biological pollution is facilitated by changes in the natural conditions of habitats as a result of physical and chemical influences. Biological pollution of the environment by pathogens of infectious and parasitic diseases of humans and animals, as well as pests and competitors of agricultural plants is considered especially dangerous. With household waste, potentially dangerous microorganisms can enter the soil - pathogenic and toxicogenic, capable of causing intestinal infections and food poisoning in humans, epidemic diseases in animals, and plant toxicosis [8, pp. 76-77]. Many microorganisms living in soils are pathogenic: they are dangerous and even destructive to humans and animals. In the process of evolutionary development and adaptation to living organisms, pathogenic microorganisms have acquired parasitic properties; they are associated with flora and fauna, can pass with soil moisture into water bodies, and be transported into the atmosphere by air currents. Disturbance of the ecological environment under the influence of various types of pollutants is one of the most important problems of our time, therefore the development of principles and methods for early diagnosis of damage to soil biota under their influence is one of the most pressing tasks of soil biology [1, 115 p].

Moving on to anthropogenic factors, in addition to agriculture and livestock farming, we can highlight the disposal of urban waste. Direct discharge into the nearest waterway without prior treatment is a very common practice that has a direct impact on soils [6, 78 p]. Wastewater can contain a wide range of contaminants, from pathogens to organic pollutants and trace elements such as chromium, copper, mercury and zinc. Mining is another major source of soil pollution in the region. The main mining activities focus on the extraction of gold, lead, nickel, silver, zinc, lithium, iron, tin, bauxite and alumina and copper. Looking at data for 2018, it is safe to say that Latin America accounts for a significant share of the world's reserves of major metal minerals, including 61% of lithium, 39% of copper, 32% of silver and nickel, 25% of molybdenum and tin [9, pp. 111-112]. Mining and oil extraction creates other environmental problems, including deforestation, which leads to loss of vegetation cover, impacts climate change, and increases soil erosion [2, 305 p].

As for other environmental problems, which are not so strong, but also affect the deterioration of soil cover, these include:

• The presence of asbestos and synthetic dyes;
• Operation of vehicles;
• Melting of glaciers;
• Military combat operations;
• Deforestation;
• Sea level rise.

Thus, after analyzing all of the above, one can understand that the current state of the soil cover of South America is of great concern. Anthropogenic factors have the greatest influence on the deterioration of the environment, which leads to irreversible consequences. The creation of protected areas and national parks, testing the performance of emission filtration and waste treatment systems, separate waste collection, rational use of natural resources is the right way to solve environmental problems.